This is a study of the neuroendocrinology of severe endogenous depression, including anterior pituitary hormone secretion patterns, their regulation of peripheral steroid hormones, and the integrity of their control mechanisms as reflected by responses to pertubation tests including thyrotropin releasing hormone, luteinizing hormone releasing hormone, and dexamethasone suppression. Both male and female endogenously depressed patients are being studied under a three day protocol with frequent blood sampling being done for the elucidation of multiple hormone secretion patterns. The patients are studied after one week of hospitalization before any treatment, after one month of tricyclic antidepressant medication of ECT, and several months following discontinuation of treatment. The patients are diagnosed according to the Research Diagnostic Criteria, and psychological ratings for degree of depression are performed at each stage of the patients' illnesses.